Metadata Report for BODC Series Reference Number 524204


Metadata Summary

Data Description

Data Category Transmittance/attenuance, turbidity, or SPM conc.
Instrument Type Transmissometer
Instrument Mounting subsurface mooring
Originating Country United Kingdom
Originator -
Originating Organization Proudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Processing Status banked
Project(s) Provess
 

Data Identifiers

Originator's Identifier tr1761.798
BODC Series Reference 524204
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1998-09-09 07:35
End Time (yyyy-mm-dd hh:mm) 1998-10-26 14:33
Nominal Cycle Interval 60.0 seconds
 

Spatial Co-ordinates

Latitude 59.32280 N ( 59° 19.4' N )
Longitude 1.01080 E ( 1° 0.6' E )
Positional Uncertainty 0.1 to 0.5 n.miles
Minimum Sensor Depth 1.0 m
Maximum Sensor Depth 1.0 m
Minimum Sensor Height 110.0 m
Maximum Sensor Height 110.0 m
Sea Floor Depth 111.0 m
Sensor Distribution Sensor fixed, measurements made at fixed depths - The sensor is at a fixed depth, but measurements are made remotely from the sensor over a range of depths (e.g. ADCP measurements)
Sensor Depth Datum Sea floor reference - Depth measured as a height above sea floor but converted into a depth relative to the sea surface according to the same datum as used for sea floor depth (applicable to instrument depths not bathymetric depths)
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
 

Parameters

BODC CODE Rank Units Short Title Title
AADYAA01 1 Days Date(Loch_Day) Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01 1 Days Time(Day_Fract) Time (time between 00:00 UT and timestamp)
ATTNMR01 1 per metre Atten_red Attenuation (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
CNDCPR01 1 Siemens per metre InSituCond Electrical conductivity of the water body by in-situ conductivity cell
PSALPR01 1 Dimensionless P_sal Practical salinity of the water body by conductivity cell and computation using UNESCO 1983 algorithm
TEMPPR01 1 Degrees Celsius Temp Temperature of the water body
 

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

Problem Reports

The salinity data do not appear credible and have all been flagged suspect.

The absolute attenuance values from this instrument should be used with extreme caution as the record started with unrealistically low attenuance values. Although the values became more realistic with time, the long-term trend in the record should be treated as suspect. The short-term signal on the other hand seems real.


Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."


Narrative Documents

TRB-1 and TRB-2 Self-recording Transmissometers

The TRB-1 self-recording transmissometer was designed by the School of Ocean Sciences, University of Wales, Bangor and was sometimes known as the 'Mark III Transmissometer'. The instrument was developed commercially by W.S. Ocean Systems Limited and marketed with the designation TRB-2.

The instrument used a 660nm (red) source modulated at 400 Hz. The optical assembly incorporated a folded beam design to reduce instrument size to a minimum. The light beam was collimated using an achromatic lens, passed through a fixed length of the water column and reflected back to a photodiode receiver via a prism reflector. The optical path length could be fixed at either 5 cm, 10 cm or 25 cm.

Data were logged at the top of each minute as the average of 200 samples taken at 400 Hz. Timing was based on an accurate real-time clock emulated by the processor BIOS extension. Data were acquired by a multi-channel 12- bit data acquisition system resident on the motherboard resulting in a count between 0 and 4095.

Data were stored internally on a 2 MByte SRAM card giving storage for 120 days of data. After deployment, the data were downloaded in a simple ASCII format onto a PC.

TRB-2 instruments could be fitted with additional conductivity and temperature sensors.

Calibration Details

Introduction

This document covers the calibration details for the TRB2 transmissometer serial number 1761.

Transmissometer

Calibration from raw counts to attenuance was made using the equation:

attenuance= -1/p *ln{(counts-BPR)/(ACR-BPR)}

where:

p = path length (m) = 0.25 m
BPR = blocked path reading (counts) = 31 counts
ACR = air correction reading (counts) = 3237.24 counts

BPR was determined prior to deployment. The instrument was calibrated against fully corrected CTD attenuance data in parallel with the Sea-Tech transmissometers (SN557,SN631 and SN637). Each instrument was strapped to the CTD frame on cast 52 of the cruise Challenger CH140. The CTD was lowered to the sea bed and brought back to 10 metres where it stayed for 30 minutes.

ACR was calculated from the inversion of the above formula using the CTD attenuance data and the corresponding transmissometer counts from the intercalibration cast.

Temperature Sensor

The temperature calibration applied was that supplied by the manufacturer:

Temp (°C)= 18.506785 + 15.381837*X + 1.692264*X 2 + 0.527669*X 3

where:

X = (2*count-4000)/2000

Conductivity Sensor

The conductivity calibration applied was that supplied by the manufacturer:

Cond (mmho/cm)= 1999.297016 + 878.983174*Y - 79.633062*Y 2 - 9.953709*Y 3

where:

Y = conductivity channel count

General Data Screening carried out by BODC

BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.

Header information is inspected for:

Documents are written by BODC highlighting irregularities which cannot be resolved.

Data cycles are inspected using time or depth series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of adjacent data sets displaced with respect to depth, position or time. Values suspected of being of non-oceanographic origin may be tagged with the BODC flag denoting suspect value; the data values will not be altered.

The following types of irregularity, each relying on visual detection in the plot, are amongst those which may be flagged as suspect:

If a large percentage of the data is affected by irregularities then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.

Inconsistencies between the characteristics of the data set and those of its neighbours are sought and, where necessary, documented. This covers inconsistencies such as the following:

This intrinsic and extrinsic screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC making are not introduced.


Project Information

PROcesses of Vertical Exchange in Shelf Seas (PROVESS)

Introduction

PROVESS was an interdisciplinary study of the vertical fluxes of properties through the water column and the surface and bottom boundary layers. The project was funded by the European Community MAST-III programme (MAS3-CT97- 0159) and ran from March 1998 to May 2001.

Scientific Rationale

PROVESS was based on the integration of experimental, theoretical and modelling studies with the aim of improving understanding and quantification of vertical exchange processes in the water column, in particular in the surface and benthic boundary layers and across the> pycnocline. PROVESS also explored mechanisms of physical-biological coupling in which vertical exchanges and turbulence significantly affect the environmental conditions experienced by the biota with particular reference to aggregation, flocculation, sedimentation and trophic interactions.

Fieldwork

The experimental phase of the project was carried out at two contrasting sites in the North Sea: the northern North Sea site (NNS) and the southern North Sea site (SNS).

The two sites had the following characteristics:

SNS NNS
Position 52° 15.0' N, 4° 17.0' E 59° 20.0' E, 1° 00.0' E
Time of year April-May September-November
Water depth (m) 16 100
M2 max amplitude (m s-1) 0.75 0.15
Max current (m s-1) 1.0 0.6
Delta T (deg C) mixed 7-1
Thermocline depth (m) mixed 35-100
Delta S 1 small
Halocline depth (m) 5-10 cf. thermocline depth
Max wind speed (m s-1) 20 25
Max wave height (m) 5 10
Max wave period (s) 8 10
Internal motion No Yes
Sediment muddy-sand muddy-sand
Biology eutrophic oligotrophic

At both locations measurements were concentrated at a central position with additional measurements being made to estimate horizontal gradients. Moored instruments (including current meters, temperature and pressure sensors, fluorometers, transmissometers, nutrient analysers and meteorological sensors) were deployed between 7 September and 5 November 1998 at the NNS and between 29 March and 25 May 1999 at the SNS. Each experiment was supported by intensive measurement series made from oceanographic ships and involving turbulence dissipation profiler CTD, particle size profilers, optical profilers, benthic sampling and water bottle sampling.

Details of the cruises were as follows:

Site Ship
(nationality)
Cruise
Mnemonic
Date
NNS Valdivia (GER) VA174 5 - 17 Sep 1998
  Dana (DK) D1198 14 - 26 Oct 1998
  Pelagia (NL) PE125 19 - 30 Oct 1998
  Challenger (UK) CH140 22 Oct - 9 Nov 1998
SNS Pelagia (NL) PE135 29 Mar - 9 Apr 1999
  Mitra (NL) MT0499 19 - 30 Apr 1999
  Belgica (BE) BG9912 17 - 21 May 1999

Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 1998-09-09
End Date (yyyy-mm-dd) 1998-10-26
Organization Undertaking ActivityProudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierPOLRIG#798
Platform Categorysubsurface mooring

PROVESS Project POLRIG#798

This mooring was also known within PROVESS as 'Rig I'. It was one of a cluster of moorings deployed at the main focus of the Northern North Sea Site in the autumn of 1998. The rig was deployed by FS Valdivia (cruise #174) in September 1998 and recovered by RRS Challenger (cruise #140) in October/November 1998.

Mooring type Surface environmental mooring with 1.9 m toroid
Instruments TRB2 transmissometer 1 m below surface
DML fluorometer 1 m below surface
NAS nitrate analyser 1 m below surface
NIOZ fluorometer 15 m below surface

Other Series linked to this Data Activity - 541963 541914 541951

Cruise

Cruise Name VLD174 (PROVESS N-1)
Departure Date 1998-09-05
Arrival Date 1998-09-17
Principal Scientist(s)Gunther Krause (Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research)
Ship FS Valdivia

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NamePROVESS Northern North Sea Site
CategoryOffshore area
Latitude59° 18.00' N
Longitude1° 0.00' E
Water depth below MSL110.0 m

PROVESS Northern North Sea Site

Nineteen mooring packages were deployed at PROVESS Northern North Sea site during the cruise Valdivia VA174 in September 1998. The layout of the mooring assemblage was L-shaped. It consisted of an heavily-instrumented site centred close to 59° 20' N, 1° 00'E (Site A with rigs A, B, Ca/b, D, E, Fa/b, G, H, I, J1, J2 and L) and secondary single-rig sites extending up to 40 km north (V and Y) and east (U and X). An addition mooring package, NIOZ or Rig M, was also deployed at Site A during the RV Pelagia PE125 cruise in October 1998.

Rigs Ca/b and Fa/b were two short-term rigs which were recovered at the end of the cruise VA174 and redeployed during the cruise Challenger CH140 in October. All the other rigs were recovered during the cruise CH140 in October-November 1998 apart from rigs H and L which could not be found and rig Cb which was trawled and recovered from Peterhead (Scotland).

The layout of the mooring array was:

BODC image

Mooring data

The data returned from each rig were as follows:

Rig identifier Data
A POLRIG#790 ADCP currents
Water level
Near-bed temperature
B POLRIG#791 ADCP currents
Near-bed temperature
Ca POLRIG#792 Near-bed temperature
Cb POLRIG#808 Rig trawled, no data returned
D POLRIG#793 Currents
Temperature, salinity and attenuance
E POLRIG#794 Currents
Fa POLRIG#795 Currents
Fb POLRIG#809
NIOZ Unknown Thermistor chain
G POLRIG#796 Meteorology
H POLRIG#797 Mooring lost, no data returned
I POLRIG#798 Surface attenuance, nutrients and chlorophyll
J1 POLRIG#799 Mid-water attenuance, nutrients and chlorophyll
J2 POLRIG#800 Near-bed attenuance, nutrients and chlorophyll
L POLRIG#801 Mooring lost, no data returned
R POLRIG#802 Water column temperature
S POLRIG#803 Water column temperature
U POLRIG#804 ADCP currents
Water level
Near-bed temperature
V POLRIG#805 ADCP currents
Near-bed temperature
X POLRIG#806 Water level
Y POLRIG#807

CTD data

A total of 352 CTD casts were also collected during the four cruises surveying this area. These include:

Cruise identifier Cruise dates No. of CTD casts
FS Valdivia (#174) 05 September - 17 September 1998 168
Dana (#1198) 14 October - 26 October 1998 51
RV Pelagia (#125) 19 October - 30 October 1998 73
RRS Challenger (#140) 21 October - 11 November 1998 60

Additonal data

Complementary meteorological and sea state data for PROVESS Northern North Sea Experiment were obtained from Marine Weather Stations located on Beryl and Frigg oil platforms in the Northern North Sea.

Other Series linked to this Fixed Station for this cruise - 517613 517625 517637 517649 517650 517662 517674 517686 517698 517705 517717 517729 517730 517742 517754 517766 518087 518099 518106 518118 524173 524185 524197 524751 524763 524775 524799 524923 524935 524947 524959 529208 529221 529233 541883 541914 541951 541963 541975 541987 553128

Other Cruises linked to this Fixed Station (with the number of series) - CH140 (PROVESS N-4) (2) PE125 (1)


BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
Blank Unqualified
< Below detection limit
> In excess of quoted value
A Taxonomic flag for affinis (aff.)
B Beginning of CTD Down/Up Cast
C Taxonomic flag for confer (cf.)
D Thermometric depth
E End of CTD Down/Up Cast
G Non-taxonomic biological characteristic uncertainty
H Extrapolated value
I Taxonomic flag for single species (sp.)
K Improbable value - unknown quality control source
L Improbable value - originator's quality control
M Improbable value - BODC quality control
N Null value
O Improbable value - user quality control
P Trace/calm
Q Indeterminate
R Replacement value
S Estimated value
T Interpolated value
U Uncalibrated
W Control value
X Excessive difference

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
0 no quality control
1 good value
2 probably good value
3 probably bad value
4 bad value
5 changed value
6 value below detection
7 value in excess
8 interpolated value
9 missing value
A value phenomenon uncertain